To rev up or not to rev up that is the question....
 

Those of you may be following my build of my VQ35DE powered 95 240sx which can be seen here:
https://my350z.com/forum/forced-indu...-clothing.html

As most of you know I plan to go FI. In preparation of this I plan to tear down the motor for rebuild to drop the compression and strengthen the motor internals. I have the option to buy everything I need to convert the motor I have from a non rev up to a rev up. I have searched this topic, but every thread I have found is more or less telling newbs what motor they have and what does it mean to have the rev up model. I was wondering is there any real benefit to this other than a higher redline and 15 more hp? Or should I save my money and upgrade else where? Do the heads flow better? Better for N/A or FI? Just trying to figure out what the overall benefit would be before I go spending the money....

I would imagine the heads are the same other then the variable exhaust cam timing. Also the timing cover is def different, dont know if that makes any difference. The block is the exact same, its not reinforced any more for the higher rpm's. Also I believe the wiring harness is different for the rev-up.


I dont care what anyone else says but I like the non-revup much better. The tork difference is night and day. If your going to build the motor and boost it then theres no point in keeping it a rev-up just for the 14 Hp. Ive heard from many Nissan Techs that the oil consumption is in the design of the rev-up heads and has to do with High-rpm's and its variable exhaust timing.

i dont really think theres a point in doing that.. i mean if you got the money then why not?... Id keep it non rev-up. Thats of course my opinion

Thanks for all your opinions I was thinking this same thing, I was just wondering what the real difference in the heads are, anyone else care to chime in?

I've heard many different reasons for the oil consumption from many different qualified people. Most of it centers around rings or valve guides... but either way, I don't think I would recommend a REVUP. Why risk using an engine with potential issues?

If you could get an HR that would be a much nicer option. It has the higher redline already built in.
And no known issues... so far. ;)

Id get a rev up or high rev just for the extra exhaust cam timing benefit for when you go turbo.

If you're going to build it anyway, it won't matter if it's a revup or non-revup.

Do you guys think if I ran rev up heads with an HR intake manifold that the head would flow better for FI?

You'd need an HR ECU to control the dual TBs, and a Revup ECU to control the exhaust timing, if you went that route -- Or do a manual TB setup... More trouble than it's worth in my opinion, if it's even possible.

You shouldnt need a HR ecu to control the dual TBs, just splice into the signal wires for the single TB to feed the other TB. So therefore you can run a Revup ECU, im just worried how the dual MAFs would react to the splice method, not sure that would work....Think you would just have to run one MAF and a "Y" split intake. But in the end probably not worth it.

You can't splice the TB/MAF inputs/outputs to the ecu. The ECU table mappings would be WAY off since it was never tuned, calibrated, or designed for dual TBs/MAFs.

That's why people who go with ITBs have to run them manually via an old fashion pull-cable and TB linkage. They get rid of the MAF altogether, and tune for MAP instead with a full standalone EMS or piggyback.

In short, you will need an HR ECU to run dual TBs/MAFs, or you will need to do it manually.

different rods bolts in the revups, different oil pumps, variable cam timing on intake and exhaust, different ecu, different wiring harnesses

no one knows. One thing is for sure...it is not a bolt on, and will further require significant mods to work. I've seen it done 1 time, but there have not been any details posted of any kind

it would work, but you'll now need injectors 2 x as big just to get things 'close' - and then tune from there. Additional cost, time, etc.

you need to set a budget and work backwards

Well unless the spacing between the heads is different than the DE the HR intake manifold will bolt right on because according to Nissan FSMs the intake manifold gaskets for both intakes are the same:

http://i23.photobucket.com/albums/b3...DEManifold.gif

http://i23.photobucket.com/albums/b3...kemanifold.gif

those are diagram #'s, not part #'s

the HR has square ports for the intake manifold, the DE has round ports...that's just one difference. The ones who have done it machined an adapter plate ( really thick one too) to make it work

Whats the benefit to square intake holes instead of round?

1) It may be due to packaging constraints to achieve a given flow area while keeping all the runners in line. The plastic probably also needs a greater wall thickness than aluminum to provide the needed strength.

2) It prevents anyone from (easily) swaping collectors from one engine to another.

Just speculation.

Maybe they are taking knowledge from ford on the 5.0.....probably not tho lol

even still they are the same, but I am guessing the heads are a little further apart they just use the same gaskets